The present invention relates to a dot mask, an assembly and a method for facilitating equipment quality control for semiconductor wafer production. More specifically, the present invention is concerned with the provision of means and a method for forming MOS capacitors on semiconductor wafers during their production, without interrupting the manufacturing process thereof.
Metal dot masks are used in the semiconductor industry to form round metal dots over an oxide to produce MOS capacitors. MOS capacitors produced in this way are for the purpose of measuring capacitance vs. voltage (CV) and capacitance vs. time (CT) parameters. The data obtained from these measurements are indicative monitors for the quality of the semiconductor production equipment, i.e., contamination in furnaces or wet stations.
From the reliability point of view of manufactured IC and similar devices, each fabrication area should run CV and CT measurements on a weekly basis. At present, the method for carrying out such measurements is to attach a hollowed mask to the wafer and to manually place the assembled mask and wafer in the sputtering chamber.
Since the modern sputtering tools use load lock chambers and different additional sputtering chambers on the way to the AlSi target chamber, it became difficult to manually insert the mask and the wafer in the desired chamber. This difficulty lead to the need to use additional metal sputtering equipment in the fabrications, only for CV/CT monitor wafers.
It is therefore a broad object of the present invention to overcome the above-described difficulties in the measurement of CV and CT parameters during the manufacture of semiconductor wafers and to provide means whereby the mask can be temporarily affixed to the wafer while moving through the sputtering chambers.